Such a process is known from EP-A-399,463. In the process disclosed therein a solution of a heterocyclic monomer is brought at a suitable temperature, after which the polymer is prepared in the presence of a suitable catalyst. The polymer formed is isolated from the reaction mixture using a centrifugation technique, following which the polymer is further purified by means of a precipitation technique.
A disadvantage of the process disclosed in EP-A-399,463 is that the resulting polymer can hardly if at all be processed, both its thermal properties and the solubility properties being absolutely insufficient for this. In addition, the reaction times of the reactions that take place are very long, and the yields of these reactions very low. As a result, large-scale application of the process as described above is not economically viable. A further disadvantage is that the heterocyclic monomer units from which the polymer is prepared is hardly if at all thermostable, so that it can be kept only if the necessary precautions are taken.